The present invention relates to the electrical interconnecting of monolithic integrated circuits, and more particularly, to interconnecting monolithic integrated circuits in a preformed interconnection structure of only a small area.
Monolithic integrated circuits must be mounted in some mechanically secure manner during use, and must be electrically interconnected with other portions of the electronic system in which it is to operate. There is a desire to accomplish this in as little space as possible and at the lowest cost possible while assuring reliable interconnection during use in a chosen environment.
A typical approach is to mount such monolithic integrated circuit chips on a printed circuit board or on a ceramic substrate. Electrical interconnections to the chip electrical terminations are made from conductive tracks provided on the surface of such board or substrate. There are limits, however, to how closely monolithic integrated circuits can be arrayed on printed circuit boards due to limitations in printed circuit board track placement technology. Closer packing is possible on ceramic substrates, but they are relatively expensive.
The density of monolithic integrated circuits across such substrates can often be increased, and the cost of mounting and interconnecting such integrated circuits on substrates and boards can be reduced through the use of chip carrier films. Such films are of an electrical insulator material having conductive interconnections provided thereon. In each "frame" along the film, an individual monolithic integrated circuit is connected to the corresponding set of interconnectors therein which radiate into the chip often bridging an opening in the film frame interior over which the chip is provided. That is, the frame interconnections from the edges of the film around the frame opening to chip electrical interconnections, the opening being provided under the ends of the tape interconnections to which the monolithic integrated circuit is interconnected and under the chip itself.
Such a film can have many frames and so many integrated circuits contained therein, one in each frame. The film with such integrated circuits can then be provided to a bonding machine which may automatically index a frame forward for each bonding, cut the tape interconnections near the edge of the film opening, and bond the remaining ends of the tape interconnections to a board or substrate to thereby interconnect the chip in the frame thereto.
Because the tape interconnections can be made quite small, some improvement in density can be achieved at least on ceramic substrates. The use of tape carrier feed in an automatic bonding machine can aid in the reduction of cost However, greater integrated circuit packing densities are desired along with a further reduction in cost.